I recently have gotten into a security craze, after a lot of research (and personal experience now) I find there is a 3 program combination that is amazing- Like many people have already said, MSE is the first I'd recommend, which that by it's self is a very good AV. If you want to go one step further, Malwarebytes is a program that specializes in... well... Malware! Lol. The last thing I recommend is the COMODO firewall. These three things work in harmony together for amazing protection. A bit of advice, I don't know for sure, but a lot of firewalls start to misbehave if you have more than one active at the same time, so I'd disable the Windows firewall.